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Date: Tue, 05 Apr 2011 19:45:51 +0300
From: Andriy Gapon <avg@FreeBSD.org>
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To: Hans Petter Selasky <hselasky@FreeBSD.org>
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Subject: Re: use_generic and usb probing
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on 05/04/2011 15:55 Hans Petter Selasky said the following:
> On Tuesday 05 April 2011 14:50:43 Andriy Gapon wrote:
>>
>> I believe that newbus already supports ordering of children on a bus.
>>
>> BTW, does USB have to pass anything from probe to attach?
> 
> Mostly only the driver info field. To avoid duplicate lookups.
> 
>> Duplicate lookup is of course not very nice, but duplicate probing pass is
>> not nice either.
> 
> This can all be avoided if the bus-drivers are sorted correctly before 
> probing!

Well, I think that that's what probe priorities actually for.
I also think that typically ivars should be set by a bus driver.  So maybe it's
not such a good idea to pass data from probe to attach via ivars in child drivers.
 But I could be mistaken about that.

Practically speaking, you most likely don't have to worry about that for drivers
that return BUS_PROBE_SPECIFIC (=0) from their probe methods.  And there is only a
few "generic" drivers that can be handled on a case by case basis.

-- 
Andriy Gapon